I have some problems with the library.
I have an arduino due and an am2301 sensor (DHT21).
The temperature at the moment that I tested the sensor was more or less 22 degrees.
I set up: #define TIMEOUT 52500 in dht.cpp
Data showned in dht_test.ino is:
Yes, the code for the support of the DHT21 is experimental, based on hints in a datasheet (link see a few pages above) and just does not work yet.
Can you please access the DHT21 as if it was a DHT22 so use read22(pin) instead of read21(pin)?
I have strong indications that the formula for DHT21 and DHT22 are identical although the datasheet hinted otherwise.
I have no confirmation yet and maybe you can confirm (as I do not have the DHT21 myself).
When my assumption is confirmed I can update the code.